I'm not using it as an example of why they're good. I'm offering it as an example because it's relevant to the topic.

Adding a cost to circumvent the law makes you less likely to do so, though. If you keep hiring people who are decidedly suboptimal because you have to use a lousy approximation of whatever characteristic you want, you might give up on it.

I get that you would rather, given that you're going to be rejected for your age/skin color/gender/etc, be told why. But if you want to reduce the use of those criteria, then banning it will stop the people who care a small amount (i.e not enough to bother getting around it.)